P Block Elements

When metals dissolve in liquid ammonia, they form solvated electrons. These solvated electrons are responsible for the characteristic blue-black color of the solution. Among the given options, calcium is the metal that forms solvated electrons in liquid ammonia, resulting in a blue-black solution. Other metals like aluminum, gallium, silicon, and germanium do not form such a solution in liquid ammonia.

The correct option is (C) : Calcium

The compound CCl F , also known as Dichlorodifluoromethane, is commonly used as a refrigerant. It is part of the chlorofluorocarbon (CFC) family, which was widely used in refrigeration and air conditioning systems. However, due to environmental concerns regarding ozone depletion, its use has been regulated and phased out in many countries. Other compounds listed, such as CCl , are not typically used as refrigerants. CCl F remains a classic example of refrigerant compounds from the CFC category.

The correct option is (A) : CCI₂F₂

Group 15 hydrides basicity trend:

• Basicity decreases down the group
• NH₃ > PH₃ > AsH₃ > SbH₃
• Reason: Decreasing electronegativity difference with H down the group
• Lone pair availability decreases with increasing atomic size

Thus, the correct option is (A): NH₃ > PH₃ > AsH₃ > SbH₃.

XeF₂ structure analysis:

• Central Xe atom with 2 F atoms and 3 lone pairs
• Total electron pairs: 5 (sp³d hybridization)
• Trigonal bipyramidal geometry (linear molecular shape)

Thus, the correct option is (B): sp³d.

Nitrogen oxide structures:

• N₂O₅: O₂N–O–NO₂ (no N–N bond)
• N₂O₃: ON–NO₂ (has N–N bond)
• NO₂: Single nitrogen atom (no N–N bond possible)
• N₂O₄: O₂N–NO₂ (has N–N bond)
• N₂O: N≡N⁺–O⁻ (has N–N bond)

Key observation: While NO₂ doesn't contain N–N bond (being mono-nitrogen), among the given options N₂O₅ is the only poly-nitrogen oxide without N–N bond.

Thus, the correct option is (A): N₂O₅.